Rotary helical gear air pump with discharge pressure regulator



July 1949. w. w. PAGET 2,477,003

ROTARY HELICAL GEAR AIR PUMP WITH DISCHARGE PRESSURE REGULATOR Original Filed July 25, 1942 B Sheets-Sheet 1 any.

July 26, 1949. w. w. PAGET 2,477,003

ROTARY HELICAL GEAR AIR PUMP WITH DISCHARGE PRESSURE REGULATOR Original Filed July 25, 1942 8 Sheets-Sheet 2 8 Sheets-Sheet 3 PAGET ROTARY HELICAL GEAR AIR PUMP WITH DISCHARGE PRESSURE REGULATOR Original Filed July 25. 1942 July 26, 1949.

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July 26, 1949.

W. W. PAG ET ROTARY HELICAL GEAR AIR PUMP WITH DISCHARGE PRESSURE REGULATOR Original Filed July 25, 1942 8 Sheets-Sheet 5 150 yen fur.-

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y 26, 1949. w. w. PAGET ROTARY HELICAL GEAR AIR PUMP WITH DISCHARGE PRESSURE REGULATOR 8 Sheets-Sheet 8 Original Filed July 25, 1942 Palented July 26, 1949 ROTARY HELICAL GEAR AIR PUDIP WITH DISCHARGE PRESSURE REGULATOR Win Withers Paget, Michigan City, Ind., assignor to Joy Manufacturing Company, a corporation of Pennsylvania Original application July 25, 1942, Serial No.

Divided and this application September- 1'1, 1942, Serial No. 458,641

4 Claims. 1

My invention relates to air pumping apparatus, and more particularly to apparatus for the maintenance of adequate pressure conditions in the cabins or other passenger compartments of airplanes which are adapted to be operated at widely varying altitudes, including high altitudes.

As is well known, it is necessary or at least highly desirable, in order that a plane may obtain the advantages of high altitude flight, to make special provision for the safety and comfort of the pilot and/or passengers. For this purpose supercharged cabins and other passenger compartments present particular advantages. While a mere displacement pump may serve satisfactorily under certain ranges of altitude as an air delivery device for a cabin or other compartment, a pump cable of the actual compression of air is more satisfactory for high altitude flight. It is desirable. in the provision oi a pumping apparatus of the compressor type, to provide a pump which shall have a large displacement in small compass, which shall be able actually to compress the air taken in through one or more compressions prior to discharge; to provide a pump which at many altitudes shall avoid the consumption of unnecessary power and the needless generation of heat by operating as, or substantially as, a mere air displacement device; to provide a pump whose speed of operation shall be automatically varied in accordance with predetermined changes in engine speed; to provide a pump which shall automatically change its characteristics from a simple air displacement apparatus to a true compressor when certain conditions obtain, such as, for example, the elevation of the apparatus to a height where the external pressure falls below a predetermined value; and to provide a pump in which, notwithstanding the automatic control of speed of operation, deliberate manual control of speed is possible.

It is an object of my invention to provide an improved gaseous fluid pumping apparatus. It is another object of my invention to provide an improved gaseous fluid pumping apparatus having an improved automatic speed control means. It is a further object of my invention to provide an improved gaseous fluid pumping apparatus having improved hydraulic speed-responsive mechanism for automatically changing the effective driving gearing therefor when the same is driven at certain predetermined speeds. It is yet another object of my invention to provide an improved gaseous fluid pumping apparatus having improved unloading means. It is still another object of my invention to provide a gaseous fluid pumping apparatus having improved controlling means for governing the operation thereof in accordance with intake pressure variations. It is still another object of my invention to provide an improved gaseous fluid pumping apparatus having improved controlling means therefor including fluid operated, speed-changing driving gearing and fluid operated unloading means both operable by a common operating medium. It is still another object of my invention to provide an improved gaseous fluid pumping apparatus of the rotary type having improved unloading means. It is still a further object of my invention to provide an improved gaseous fluid pumping apparatus having improved means for lubricating the same. A further object of the invention is to provide improved gaseous fluid pumping apparatus having improved governing means. Another object is to provide a compressor having improved speed control means operative to effect a reduction in the speed of the compressor when the compressor speed reaches a predetermined value. Still another object is to provide a compressor connected through drive gearing to power means and having improved control means operative at a predetermined compressor speed for changing the drive gearing to effect a slower driving of the compressor. Yet another object of my invention is to provide a compressor having improved means operating at a predetermined low intake pressure for effecting an increase in the pump discharge pressure. Other objects and advantages of the invention will hereinafter more fully appear.

This application is a division of my copending application Ser. No. 452,299, filed July 25, 1942.

In a preferred embodiment of my invention, a pair of intermeshing rotors may be supported within a casing and operate when driven to deliver air from an intake at one point in the easing to a discharge port at another point in the casing. The rotors may desirably be provided at one end with shafts having gears mounted thereon for transmitting power from a. drive shaft to the rotors and for maintaining the rotors out of contact with each other but in such close relation that space packing is provided. A pair of the gears may be alternatively connected in driven relation to the drive shaft for effecting drive of the rotors at different speeds. Desirably, there may be connected to rotate with one of the rotors a speed responsive device for governing a valve mechanism for controlling the flow of an operating fluid relative to a fluid actuated clutch mech- 'anism which is operable to connect one of the two gears last mentioned in driven relation with respect to the drive shaft. At comparatively low rotor speeds, such valve device may desirably operate to supply fluid to the clutch mechanism in such a manner as to eil'ect a connection of that gear which drives the compressor through a high speed gear ratio. when the rotor speeds reach a predetermined value, the speed responsive device desirably operates to vent fluid from the clutch operating mechanism thereby to disconnect the high speed gear and to permit drive to be transmitted through the other of said pair of gears to the rotors. Desirabiy, manually operated valve means are included for removing the control of the fluid flow from the speed responsive device operated valve and for controlling directly the flow of fluid relative to the clutch mechanism at will. Further, there is desirably associated with the compressor a control mechanism operative when the compressor intake pressure is above a predetermined value to effect compressor dischage at a relatively low pressure, and in a preferred form, without any compression, while upon a predetermined decrease in the intake pressure the control means operates to preclude discharge by the compressor without a substantial compression of the fluid taken into the same. Desirably, such control device may take the form of a valve mechanism for controlling an auxiliary discharge opening arranged in such relation to the casing that the same has communication with the", rotor pockets well prior to the attainment of sald pockets to the normal discharge opening, and a-valve device for controlling such opening. Advantageousiy the valve device may be controlled y lubricant pressure provided by the lubricating s stern of the compressor.

Further in the preferred embodiment there may be a common hydraulic system for the speed control and compressor discharge pressure control mechanisms of the compressor unit, such hydraulic system preferablyutilizing the lubricant of the compressor whereby a single pump may supply pressure for operating change speed gearing and valve mechanism for controlling the compressor delivery pressure and supply the lubricant to the lubricated portions of the compressor.

In the accompanying drawings there are shown for purposes of illustration one form and a modiflcation which the invention may assume in practice.

In these drawings,

Fig. l is a side elevation of the complete apparatus.

Fig. 2 is an end elevation of the apparatus of Fig. 1, viewed from the left-hand end of Fig. 1 and showing the drive end of the apparatus.

Fig. 3 is an opposite end elevation of the apparatus shown in Fig. 1, being an illustration of the right-hand end thereof.

Fig. 4 is an enlarged central longitudinal vertical section on the plane of the line 4-4 of Fig. 2.

Fig. 5 is an enlarged horizontal fragmentary sectional view on the plane of the line 5-5 of Fig. 3, showing a detail of the hydraluic system.

Fig. 6 is a horizontal longitudinal sectional view on the planes of the line 6-6 of Fig. 4, with parts shown in elevation.

Fig. "l is a view showing portions of the unloading mechanism shown in Fig. 6 in different positions and with certain additional parts shown in elevation.

4 ofthelinel-lofFlg.6,withpartsshownin full.

Fig. 9 is a vertical transverse sectional view on the plane of the line 0-8 of Fig. 6, showing a detail of construction of the unloading mecha- Fig. 10 is an enlarged fragmentary sectional view showing venting means for the unloading valve operating cylinder, the view being taken substantially on the plane of the line l0l| of Fig. i.

Fig. 11 is an enlarged horizontal sectional view through the control mechanism at the righthand end of the apparatus, the view being taken on the same plane as Fig. 6.

Fig. 12 is a fragmentary vertical transverse section on the plane of the line |2-l2 of Fig. 11, showing a manually operable control valve positionable to vary the speed of drive of the pumping apparatus.

Fig. 13 is a section on the lines ll-II of Fig. 12.

Fig. 14 is an enlarged detail sectional view on the axis of the speed-responsive device for controlling the speed of drive of the apparatus.

Fig. 15 is a transverse sectional view taken on the plane of the line 15-" of Fig. 14.

Fig. 16 is a fragmentary view generally similar to Fig. 14 but with parts shown in elevation and illustrating a different position of the parts.

Fig. 17 is a detail longitudinal sectional view on the plane of the line l'l-il of Fig. 15.

Fig. 18 is a fragmentary detail view showing ;a locking screw for the governor. I Fig. 19 is an enlarged horizontal sectional view on the same plane as Fig. 6, showing details of construction of the external pressure-responsive unloader valve controlling pilot mechanism.

Fig. 20 is a fragmentary view on the same plane as Fig. 19, showing the parts in diiierent relative positions.

Fig. 21 is an enlarged transverse vertical section on the plane of the line 2l2l of Fig. 4.

Fig. 22 is a longitudinal view on the line 22-22 of Fig. 21.

Fig. 23 is an enlarged fragmentary sectional Fig. 8 is a vertical sectional view on the plane 15 view on the plane of Fig. 4, showing details of the speed-controlling drive clutch.

Fig. 24 is a vertical sectional view on the plane of the line 24-24 of Fig. 4, showing a, portion of the driving gearing.

Fig. 25 is an enlarged transverse fragmentary sectional view showing a detail of the drive mechanism.

Fig. 26 1s a fragmentary section on the plane of the line 26-26 of Fig. 25, showing a detail of a roller ratchet.

Fig. 27 is a section on the line 21-21 oi Fig. 25, showing another detail of the roller ratchet mechanism.

Fig. 28 is a vertical sectional view on the plane of the line 2828 of Fig. 6, showing the high pressure head of the pump.

Fig. 29 is a vertical transverse section on the plane of the line 29-49 of Fig. 4.

Fig. 30 is a vertical sectional view on the plane of the line 38-30 of Fig. 4, showing the intake end of the rotor chamber.

Fig. 31 is a view similar to Fig. 29, showing a modification.

In the preferred embodiment of the invention shown, the pumping apparatus. generally designated C, comprises a main casing part 3i and a pair of coacting rotors 32 and 33. The rotor 32 is a male rotor and comprises fo r helicaliy arranged lobes II, the rearward sides iii gar-1,00:

of which are shown as generated curves in profile, while the leading or pressure side 36 of each of these lobes is, in profile, substantially in the form of a circular arc. The female rotor 33 is provided, in the form shown, with six helically arranged grooves 11 each adapted to cooperate with the lobes of the rotor 32, and the leading concave surfaces 38 of the grooves 31 are in profile substantially in the shape of an arc to coact with the arcuate pressure surfaces 38 of the lobes of the rotor 31, while the following concave surfaces 39 of the grooves 31 are generated curves in profile. It will be understood that with a device of this character, a materially shortened sealing line is had for the pockets or working spaces which are formed by the coaction of the rotors with each other. A different form of rotor construction 'may be used without departing from various aspects of my invention, as for example that construction which is shown in Fig. 31, in which the rotors 32' and 33' have their respective lobes 34' and grooves 31' formed with generated surfaces in a well known manner. With rotors constructed and arranged as illustrated, it will be evident that they will have, as it were, low pressure and high pressure ends.

In either case, the rotors are adapted to operate with space packing; that is to say, they are maintained in such relation to each other, through gearing, that there is no actual contact between the rotors with each other. Each of the rotors 32, 33 is herein shown supported at its ends by stub shafts, the rotor 32 having a stub shaft 40 at its low pressure end and a stub shaft 4i at its high pressure end; while the rotor 33 has a stub shaft 42 at its low pressure end and a stub shaft 43 at its high pressure end. The stub shafts 40 and 42 are supported in suitable bearing sleeves 44 and 45 supported in bores 46, 41 in an integral end casing portion 48 formed in one piece, as herein shown, with the housing 3|. A separate, plural-part head 50 supports ball thrust bearings 5| and 52 in which the stub shafts 4i and 43 are respectively mounted. These bearings position the rotors so that no contact can take place between them and the ends of the casing. The casing 3| is provided with an intake chamber 53 with which an intake passage 54 provided with suitable strainer or other devices, not shown. for preventing the ingress of harmful material, communicates, and the intake space communicates with the right hand, low pressure ends of the rotors, and also for a substantial part of the length of the rotors communicates with the back portions thereof so-to-speak, the portions at the opposite side of the plane which includes the rotor axes, from the discharge. The intake chamber 53 also includes curved recesses 53' extending substantial distances arcuately, the extent of these recesses being such that, in the illustrative embodiment shown, the intake chamber and its component recesses 53 provide intake communication with the rotor chambers over arcs of considerably more than 180. The extent of the intake port, from the functional aspect, is, with the proportions shown, such that the "trailing" edges of the grooves 31 and of the spaces between the lobes 34 pass out of register with the intake port just before engagement or the start of compression within the tooth grooves and spaces begins. It will be evident, however, that a small amount of overlapping, so-to-speak, would be possible and to depend on the dynamic effect of the incoming air to offset the tendency toward a reversal of flow caused by the initial compresslon. The casing ii is provided with a discharge chamber 55 at the left hand (high pressure) end of the rotors, and another chamber 66, whose purpose will later be described, communicates with the chamber 55 though it is separated therefrom for a substantial distance by a web 51. The discharge chamber communicates with the high pressure ends of the rotor chambers, as shown in Fig. 28, and also with said ends through a peripheral opening in the rotor casing as indicated by broken lines in Fig. 1.

For the purpose of maintaining the rotors out of contact with each other they are connected by intermeshing helical gears 60 and GI, the gear '60 being splined, as at 62, to the stub shaft II, and the gear Bl being splined, as at 63, to the stub shaft 43. The gears '60 and GI are so formed that their helix angles correspond in hand and lead to the helix angles of the rotors to which they are respectively fixed. Regardless of the speed at which the rotors turn, these gears operate to maintain the space packing heretofore referred to; in other words, a very small clearance between the surfaces of the lobes and the sides and bottoms of the grooves of the rotors is maintained, thus preventing wear and permitting the operation of the pump at a speed far exceeding any permissible with rotors running in contact with each other. By reason of the smallness of the clearance maintained and the high speeds of rotation, serious leakage is prevented.

The feature of meshing rotors held out of contact by helical gears of the same hand and lead as the rotors is claimed in my copending application Ser. No. 623,485, filed October 20, 1945.

A drive shaft 10, preferably driven through a flexible non-back-lash drive such as, for example, that disclosed in my application Serial No. 443,414, filed May 18, 1942, now abandoned, is arranged in alinement with the stub shaft 43 and has a driving connection therewith as shown at H. The drive shaft is journaled by means of a ball bearing 12 carried by the plural-part head 50 and engaging a cylindrical portion 13 on the drive shaft. Its other end is rotatably supported as later described. Surrounding a cylindrical hub portion 19 of the gear BI is a bearing sleeve 80, and a cylindrical portion ill at the right hand end of the drive shaft Ill rotatably surrounds the bearing sleeve and is journaled thereon. Keyed to the periphery of the cylindrical portion 8| of the drive shaft is a member 82 having a number of recesses 83 formed therein receiving rollers 84 which are operative, as later described, at times to effect a clutching between the member 82 and a cylindrically bored liner ring 86 keyed, as at 81, to the gear iii. The recesses 83 have relatively straight base surfaces 90 and radial surfaces 9|. Through the latter surfaces there project spring-pressed plungers 92 adapted to act upon the rollers 84 and cause them to connect the members 82 and upon predetermined relative rotation between the latter members. Springs 93 act against cross pins 94 and move the plungers 92 against the rollers 84. The pins are supported in end closure or plate members 91 and 98, and the rollers have stems 99 loosely received in openings I00 in the plates 91 and 98. These plates 91 and 98 are supported to turn with the member 82. It will be evident, referring to Figs. 24 and 25, that if the member 82 be driven counterclockwise it will, through the rollers 84, be connected to the liner ring 86 and through the latter drive the gear BI, and by virtue of the connection of gear il to shaft 43 drive the rotor 33, while through the meshing of gear I with gear 33 and the mounting oi gear ill on shaft lI. rotor 33 will also be driven. If the gear il be driven counterclockwise at a greater angular rate than the member 32, it will not be connected to that member and may turn freely in the direction mentioned. relative to it.

It will be noted (Fig. 4) that the stub shaft II has another shaft I32 connected with.it by means oi a splined connector element I33 which has an axial bore III for reasons later explained. The left-hand end of shaft I32, as viewed in Fig. 4, is iournaled in a ball bearing I33 carried by the plural part head 50, and carries a gear IIIl somewhat smaller than the gear Gil. A gear I53, somewhat larger than the gear 3 I, meshes with the gear IIII and is journaiied by a ball bearing III) on 0, cylindrical portion III of the drive shaft II. It also has a sleeve portion I I2, internally splined at I I3 and supported by a ball hearing I II on a further cylindrical portion II5 of the drive shaft 13. Discs II'I connected to the sleeve portion II2 are interleaved with other discs II! connected by splines II! to the drive shaft III. which has a flange I adjacent the hearing I II serving as an abutment for the end one of the interleaved series of discs H1, H3 when these are pressed together to connect the gear I33 to the drive shaft I3. A follower member I22 is slidably supported on a packing ring I23 mounted on the shaft I3 and has an annular outer sleeve portion I24 with whose bore a peripherally packed plate I25 coacts to form a chamber I23 for clutch applying hydraulic pressure. A ring I21 seated in an internal groove in the sleeve portion I23 provides an abutment for a flexed annular spring I23 whose opposite side presses upon the side of the plate I25, and the spring I23 normally maintains the follower member I22 in clutch unloading position.

It may now be noted that when the clutch is loaded, the gear I03 will be connected directly to the shaft 13 and will drive the gear I31 and so the gears 53 and GI, and thus the rotors 32 and 33: and because the gear 5| will then be rotated faster than the member 32, and in the same direction with the latter, there will simply be an overrunning clutch action and no tendency for connection between gear 3| and member 32.

It will be evident from what has been said that the drive shaft in is rotated counterclockwise in Fig. 2 and that the rotors 33 and 33' turn clockwise in Figs. 29 and 31 while the rotors 32 and 32 turn counterclockwise in the same figures, and that air taken in through the intake onnec tion 53 is entrapped between the casing and the rotors and is progressively moved, and if it remains entrapped, compressed as it is moved to the discharge connection 55.

The compressor has automatic means for effecting change in the manner (and accordingly in the speed) of drive thereof governed by a speed responsive device and it has automatic means for effecting the initiation oi compressive action thereby governed by the pressure of the air surrounding the airplane. Both of these automatic means are hydraulically operated, so, having described the hydraulic clutch operating means which effects high speed drive of the compressor, I shall briefly describe the hydraulically controlled means for initiating compressive action, and then describe the hydraulic system and its controls which eil'ect the operation of the clutch and the unloading means.

Referring particularly now to Figs. 6, 28, 29,

30 and 31, it will be observed that the casing 3| at the intake side does not fit at all closely to the peripheries of the rotors, and that there are. m previously described, arcuate intake grooves 53' which extend at the intake end of the p p somewhat more than in one case and somewhat less than 90 in the other past the plane which includes the axes of rotation of the rotors. but that there are wall portions respectively marked I32 and I33 which except for clearance adequate to constitute space packing do conform or fit quite closely to the cylinders traced by the outermost portions of the rotors and that these portions I32 and I33 intersect along a line I33 parallel to the rotor axes. Now, the fluid which is sealed" in the successive progressively diminishing chambers between the rotors and the casing walls would be substantially compressed if no escape or discharge were provided between the times pairs of tooth spaces or grooves move out of communication with the grooves 53' and the instant that the leading edges of the tooth spaces come into communication with the discharge 55; and under certain conditions such compression is very desirable. But under other circumstances it is better to avoid material compression and thus conserve power and avoid unnecessary heating of the cabin. Accordingly, I have provided an opening at I35 so related to the length of the casing and the helix angle of the rotors that when the opening I35 is unobstructed no compression of the fluid enclosed between the rotors 32 and 33 will take place before communication with the opening I35 is had; and the relationship of the opening I35 to the discharge passage 55 is such that the air remaining in the pockets in the rotors as these pockets move out of communication with the opening I35 will not be compressed before these same pockets communicate with the discharge 55. It may thus be noted that the position of the ends of the intake grooves 53' and the position and dimensions of the opening I35 are such that with the helix angles of the rotors used, tooth pockets whose "trailing" edges are Just ceasing to communicate with the intake are just about to commence to have their forward edges pass over the opening I35; and that as the trailing edges of tooth pockets approach their points of final communication with the opening I35 when the latter is open they have their leading edges pass beyond the edge of the final discharge opening, whereby there is displacement, but not compression, of fluid when the opening I35 is not closed by the valve I35. However, when valve I33 is closed, there is a substantial compression of the fluid between the time the tooth spaces cease to communicate with the grooves 53' and move into communication with the discharge 55.

To control the opening I35, which has a peripheral wall which lies in the surface of a cone, I have provided a valve I35 whose shape is such that when the same is closed it conforms very closely to the walls I32 and I33, as may be seen in Fig. 9. This valve has ears I31 through which pins I33 pass, and these pins are secured in the arms or flanges I39 carried upon a pivotal support member I" which is secured, by a pivot pin Ili, to the wall of the casing 3i. A shoulder I32 on the valve and a shoulder I43 on the casing limit the closing movement of the valve I33 to a position in which the walls of said valve conform exactly to the surfaces of the rotor chambers. This valve is adapted normally to be maintained open by a spring I45 engaging at one end the wall of a member I45 which forms a portion of the enclosure oi. the discharge chamber 55 and which is secured, in any suitable manner, to the casing The other end of the spring acts against a piston I41 having a packing I fitting the walls of a cylindrical chamber I49 which is formed in a cylinderproviding member I50 also secured, in any suitable manner, to the casing 3| in a position overlying the member I45. A piston rod or operating stem I52 with an elongated eye I53 is connected at its outer end to the piston I41, and by means of the eye and a pin I54 is connected to the valve I35. The piston I41 and the member I50 cooperate in forming a servo-motor I55 to which fluid may be admitted through a connection or passage I55 under a control hereinafter described, and a leakage port I58, shown in Fig. 10, is provided to conduct any liquid which may escape past the packing I40 to an oil sump I50 in the lower part oi the casing 3|. When the servo-motor I55 is not under pressure de livered through the passage I55, the valve I35 may be moved to the open position shown in Fig. 7 by the spring I45, and in that inclined position it will offer very little obstruction to the discharg of fluid to the chamber 55 and thence to the interior of the cabin through any appropriate connection. When, however, pressure is supplied under certain predetermined conditions to the servo-motor I55, the piston I41 will be caused, through the operating stem I52 and the pin I54, to close the valve I35, and the compressor will then operate substantially precisely as though there were no opening I35 available. Thus depending upon the position of the valve I35, there is provided by the single unit in effect a. mere displacement pump and a compressor capable of substantial compression of air taken in. That this compression may be in practice from one very substantially subatmospheric pressure to a higher one which is itself less than atmospheric does not, of course, alter the fact that there is a definite compression.

As previously indicated, the change in speed of operation of the compressor and the loading and unloading are both hydraulically controlled, and I shall now describe the hydraulic system. There is provided in the base of the casing III the sump I50. This sump is disposed between the lower wall of the rotor housing and an outer wall I5I forming an integral part of the casing 3I. The chamber is, in the horizontal position of the compressor, substantially horizontal, and a pump of the intermeshing gear type is positioned at the right-hand end of the casing as the same is viewed in Fig. 4, so that it is partially submerged and so that its intake is always submerged (in the horizontal position of the casing) in the oil in the sump. This pump, designated I52, includes a casing I53 having intersecting rotor chambers I54 therein in which are rotors I55 having intermeshing teeth I55 arranged at a slight angle to elements of the cylindrical surface in which the outermost points in the rotor teeth lie. An intake passage I51 conducts oil to the lower sides of the rotors I55, and the oil is carried around by the teeth I55 and is discharged to a discharge space I58 above the plane of the mesh line of the rotors I55. One of the rotors I05 drives the other, and the first mentioned rotor is provided with a shaft I50 which extends through a ported cover plate I10 and carries a gear I1I which is in turn driven by a pinion I12 10 rotatably supported on a sleeve member I13 later more fully described. A larger gear I14 is herein shown as formed integrally with the gear I12, and the gear I14 is driven by a pinion I15 formed integral with the stub shaft 42 and arranged at the extreme right-hand end of the latter in Fig. 4. A clean-out plug I10 is arranged below the oil pump in the bottom of the sump. The discharge passage I50 communicates with passages I10 in the cover I10, and I10 in a supplemental cover, and opens into the bore I of the sleeve member I13 previously described. From this latter the fluid is discharged through branch passages IOI into a chamber I82 containing a strainer structure I03. Between the ends of the chamber I02 and suitably associated with the strainer is an annular peripheral member having a peripheral groove I84 to which the strained lubricant obtains access through radial ports I85. The annular groove I04 communicates with a passage I85 which opens into an annular groove I01 surrounding the bearing bushing 45. The opposite side of the annular groove I01 opens into a passage I00 whose upper end opens into a chamber I00. The chamber I00 constitutes a distribution point for oil for lubricating purposes and for operating the speed-changing clutch mechanism previously described and also for fluid for closing the valve I38 previously mentioned. In line with the passage I80 there is another passage I opening outwardly and upwardly from the chamber I83. This communicates with an annular groove I02 in the bushing 44. The annular groove has continuously in communication with it obliquely disposed passages I 03 opening into a chamber I04 in the stub shaft 40. The chamber I04 is connected by a tube I 05 suitably centered as at I05 within the rotor 32, and at the left-hand margin of Fig. 4 the tube I 05 opens into a chamber I01 in the stub shaft 4I. As will be apparent from what has been previously described, the chamber I01 communicates through the passage I04 with a hollow interior I90 of the shaft I02 and discharges through the left-hand end of the latter, as shown in Fig. 4, into a chamber I00 formed in the multipart head structure 50. Fluid is delivered from the chamber I00 through a lubricant tube 200 into a chamber 20I between the rotor casing and the chamber I09 and which forms an enclosure for the motor driving gear earlier described. The lubricant tube 200 has two discharge orifices 202 and 203 which respectively discharge lubricant onto the peripheral surfaces oi the couples I01, I08 and 50, 0I thereby keeping the gear couples 50, 5| and I01, I00 adequately lubricated. The lubricant, after its discharge over these gears, passes downwardly within the chamber 20I and is conducted out of the casing through a passage 205 and a tube 205 of small diameter opening through the side Wall of a larger tube 201 back into the sump I50. Lubricant is also discharged directly through the tube 201 back into the sump I50. The presence of the branch tube 205 of small diameter prevents all of the lubricant in the sump I50 from flowing into the chamber 20I when the airplane has occasion to make a dive and interfering with the operation of the drive mechanism for the rotors. Another drain plug 200 is arranged in a position to permit the draining of lubricant from the chamber 20I.

It will be noted that in the stub shaft 40 there is, at the right-hand end of the chamber I04, a partition 2I0 to the right of which there is a valve-receiving bore 2. Other obliquely extending passages 2|2 connect the annular grooves I92 with the bore 2 at points near the partition 2"), and a further annular passage 2|! formed in the bushing 44 is connected with the interior of the bore 2 by radial passages 2M. Suitably supported on the rear end of the stub shaft 40 is a mounting 2|i for a speed-responsive governor 2H5 which serves in conjunction with a spring 2|l housed in the interior of a valve member 2|8, to vary the position of that valve member in the bore 2| I. The valve member will be observed to be open from end to end, as at 220, and to house the spring 2" within it in such a, manner that the spring acts on the righthand end of the valve in Fig. 14 at one end and at its other end acts on the partition or wall 2|0. The valve has a left-hand end collar 222, another annuiar peripheral collar 223 spaced by a, groove 224 from the collar 222 and a further enlarged collar-right-hand portion 225spaced by a peripheral groove 226 of substantial length from the collar portion 223. The support member 2| 5 has a portion 221 guidingly engaging the head 225 and is traversed by openings 222 so that in certain positions of the valve 2|! there may be a, discharge into a chamber 230 at the right-hand end of the compressor, of fluid entering the chamber 2 through the radial passages 2.

The governor support 2li includes fly weights 232 pivotally supported on transverse pins 223 in earlike portions 2 carried by the support 2|. Portions 235 of the fly weights at the opposite side of the pivots thereof from the main masses of said fly weights carry adjustable screw devices 236 which have heads 231 adapted to engage the end surface of the head 22!, and upon the attainment of the shaft 40 to a predetermined speed of rotation the fly weights actuate the portions 2" to move the valve 2|! to shift the valve from the position shown in Fig, 14 to that shown in Fig. 16, thereby allowing fluid entering the bore 2 through the radial passages 2 to be vented while at the same time preventing any delivery of fluid from the pump to the radial passages 2". The cutting off of the supply of fluid to the radial passages 2, and the venting of fluid from these passages through the bore 2|| will effect, as shortly described, a reduction in the speed of the rotors. This reduction in speed, however, will not be sui'llcient to effect an operation of the speed governor permitting the valve to move again to a position for supplying fluid to the passages 2, as the design of the governor is such that it becomes operative to force the valve 2|il to the left only upon the attainment of a speed as of the order of 7000 R. P. M., while after once assuming the position of Fig. 16 a falling oil of the speed to a lower speed of the order of 4000 R. P. M. will be necessary before the weights will be moved in and permit the ieestablishment of fluid delivery to the cham; -er I26 of the hydraulically operated clutch mechanism.

The circumferential groove 2|5 is connected below the stub shaft 40 with a passage 2" which extends downwardly parallel to the axis of the passage I90 and opens through an opening 242 into the interior of the bore of a valve-receiving bushing 243. This valve-receiving bushing contains a rotatable valve 2, which is used primarily for testing purposes and which has an operating handle 2" by means of which the valve may be turned into any one of three different positions. In the position of the valve 2, shown in Fig. 4 and in Fig. 11, a diametric passage 24' connects the opening 242 with an opposite opening 241 in the valve sleeve and via the latter opening to the passage 2" which is connected through a port 2 in the bearing sleeve 1 and an annular groove 250 and radial passages 25| with a chamber 252 within the interior of the stub shaft 42. The outer end of this chamber 252 is closed by a plug 253, while the other end of the chamber 252 is connected by a suitably centered tube 255 with arrangements for effecting the operation of the clutch mechanism previously described and for the performance of certain lubricating functions. Before proceeding with the description of this mechanism, it may be pointed out that the valve 2" at speeds of the rotor 22 below a predetermined number of R. P. M, will be in the position shown in Figs. 4 and 14 and will connect the pump discharge through the ports and passages previously described with the tube 255, but that at speeds above such a predetermined number of R. P. M. the valve 2|! will assume the position shown in Fig. 16 and cut of! communication completely between the passages I90 and 2 and to vent 2 back to the sump through the chamber 230. Now it will be observed, referring particularly to Fig. 4, that at the rear end of the tube 255 there is a bell or funnel shaped member 251 fitting the bore 2" of the stub shaft 42, and that a split spring ring 25! operates to prevent possible movement of the member 2" out of the bore in the stub shaft if any loosening should occur. Within a stepped bore 200 within the drive shaft 10 there is arranged a hollow plunger member 2" which is provided at one end with a perforated flange 2B2 adapted to seat against a split ring 28! secured within the inner wall of the drive shaft Ill. The plunger member I is engaged by a spring 2 which reacts against a shoulder 22! within the drive shaft, and a thimble 260 closes the left-hand end of the chamber within which the element 2" is movable. The interior of the chamber communicates, through obliquely radially extending passages 261, with the outside of the drive shaft between the ball bearings 12 and H0. Other radially obliquely extending passages 268 connect the interior of the stepped bore 260 at the right-hand end of the plunger member 28| in communication with the chamber I20.

The mode of operation of the mechanism which has just been described is as follows: When the compressor is started. a driving connection is immediately established between the shaft II and the gear BI and the pump I82 commences to deliver fluid through the strainer, through the passage I26, the chamber ill, the passage "I, the oblique passages M2, the annular groove 22!, the radial passages 2H, passages 2H, 2, 2, 2H and the tubular conduit 25! to the interior of the member 251 and to the space between that member and the plunger member 26 The fluid immediately passes through the perforations in the flange 262 and through the radial passages 2" into the chamber I20 and brinss the clutch discs H1 and II! into contact with each other As the oil continues through the tube 2", the member 2" moves to the left compressing the spring 2, and the compression of this spring is so determined that the clutch pressure will be gradually applied as the member 2I| moves to the left.

When this member reaches its extre e left-hand position, the clutch discs may be firmly pressed against each other and drive of the rotors at the higher speed. when the gear I is the driving element, will be effected. It will be appreciated that this high speed driving will be continued until the speed of the compressor builds up to such a degree that the valve 2l8 will be shifted by the governor, and then the slower speed drive between the shaft and the compressor will be initiated. It will be noted that lubricant will be supplied from the space between the member 256 and the member 251 to the splines.

The feature of the control means for the clutch comprising discs II! and H8 is claimed in my copending application Ser. No. 80,844, filed March 11, 1949.

The manually operable valve 2 previously mentioned can be adjusted as previously described to such a position as to eral passage 210 which opens into the space 21! at the right-hand side of the valve, a space which is connected by a passage 272 (Fig. 4) with the chamber 230 which communicates with the sump. When the valve 2 is turned to bring the passage tion of the valve opposite the groove 210, be evidently impossible to transmit pressure through the tube 255 for effecting high speed drive of the compressor. The valve 244 also has surrounds the sleeve 243 and which is connected at its opposite side with a passage 28!. The function of the spring loaded valve 218 is to maintain a suflicient pressure in the chamber I 89 under all circumstances when the compressor is rocates in the bore. of the bore and leads into the space 230, and a spring 285 having an adjustable follower 280 is adapted to control the pressure in the passage 20!. The passage 28l communicates through a port 208 with a bore 299 of a valve seat member 290 mounted in a passage 29! which is connected by another passage 292 ing to the chamber I59 from the bore 209 is prevented fluid will be supplied to the servo-motor IE5 at a pressure determined by the valve 203 and that again, subject to the same condition, the valve I36 would be closed whenever the pump I02 was of the casing 31. An adjustable closure element and spring tension regulator 30! engages a spring 302 which acts upon the valve 291 and normally tends to seat it. Connected to the valve 291 and to the sleeve member 299 at opposite sides of the sleeve portion 298 are bellows devices 303 and 304 bounding a chamber 305 in which the sleeve 298 is enclosed, and this sleeve is perforated so that free communication may at all times exist throughout the interior of this chamber. The chamber 305 is evacuated, and the compression of the spring 302 is so determined that until the pressure acting upon the exterior of the belpressure in the casing 300 falls below a predetermined value. the valve 291 will promptly seat and interrupt the discharge of fluid back to the sump and cause the building up of such a pressure in the chamber I55 as to close the valve I36 and cause the compressor to operate as a "compressor instead of a displacement means. It will be noted that the walls of the casing 300 are perforated as at 309, 3| 0 to permit the pressure device of any suitable construction as shown at 3, and a nects the chamber 2!" tion of the compressor, namely, in this case, the intake pressure. The setting of the spring 302 is such that the valve 291 is normally open at heights of the airplane below 25,000 feet. The valve 291 is of the "overbalanced" type, being of the sharp opening variety, so that when the valve I36 is to open, it

sage 3|2 acts against the outer end of the valve and counteracts inner end of the valve produced by the fluid acting through the ports 294.

It will be noted that the rotor 33 is hollow irom end to end and that passages 3H, 3 connect the space surrounding the left-hand stub shafts I, 43 with the interior of the rotor, while passages Iii extend through the stub shaft 42, so that any tendency of lubricant to enter the rotor spaces is prevented by pressure equalization. The casing St has cooling fins Sit.

An extended summary the mode of operation of the illustrative embodiment and modification of the invention which have now been described in detail is not necessary in view of the explanations given of the modes of operation of the component parts. It may be noted, however, that when the airplane takes oi! the compressor will have the valve I36 open and will simply move large quantities of air at take-oi! conditions into the cabin. The cabin will be provided with suitable automatic vent mechanism, such for example, as that which forms the subject matter of my application Serial No. 443,513, filed May 18, 1942, for Pressure control devices, so that the cabin pressure will not build up obiectionably. When the compressor is caused to rotate, it will be started initialLv at the slower speed, drive being from the drive shaft Ill through the automatic roller clutch mechanism to the gear 6i. As soon as the compressor has operated long enough to produce the necessary oil pressure in the system-a thing which occurs almost instantly--the high speed drive of the compressor rotors will be initiated unless the manual control valve 2 should have been moved to prevent this-an unlikely condition as this valve is used mainly for test purposes. Obviously, it a substantial period of idling is desired prior to take oil, this valve could be so manipulated as to prevent the needless displacement of air by the compressor. As soon as the compressor driving speed attains to a certain predetermined number of R. P. M., the automatic speed governor mechanism will shift the valve 2|! to substitute the low speed drive for the high speed drive by interrupting the supply of clutch loading pressure to the friction clutch loading member I22. Thus during the relatively high speed operation of the compressor during flight the low speed drive will be in operation. The nature of the governor is such as to avoid hunting, and when the speed oi the compressor is brought up to a. value suflicient to initiate low speed drive there will be required a greater reduction in speed than will be occasioned by the change from one drive to the other before the compressor will again shift back to the high speed drive. If the airplane rises to the requisite height so that compression of the air instead of displacement thereof is necessary for satisfactory operation, the evacuated bellows will permit the closing of the valve 291 and there will be fluid supplied to the piston ll! of the servo-motor I, and the valve I36 will be closed and the compressor will then operate to compress the fluid, and all oi the fluid taken in will be discharged through the regular discharge passage 55. It will be evident that the compressor will be adequately lubricated at all times and that a pump of the character shown has such capacity for the moving of lubricant that a very efiective delivery of lubricant to the points requiring lubrication will be assured.

As a result of this invention it will be noted that a novel air pump or compressor is provided having novel control mechanism. It will further be evident that by the provision of the novel construction and arrangement of parts, an air pump or compressor is provided which is extremely compact and relatively light in weight. It will also be noted that by the novel manner of association of the pump and its control mechanism with the cabin of an airplane it is, through association with automatic vent valve devices such as the one disclosed in application Ser. No. 443,413, possible automatically to regulate the cabin pressures to accommodate for any changes in air pressures externally oi the cabin, thereby to enable the airplane to operate at relatively great heights, or at any lower ones. The novel control features of the invention enable an airplane to operate at high altitudes with safety and with comparative comfort for the cabin occupants and with good economy. Other uses and advantages of the invention will be obvious to those skilled in the art.

This application is a division of my application Serial No. 452,299, filed July 25, 1942, Air pumping apparatus.

While there are in this application specifically described one form and a modification which the the invention may assume in practice, it will be understood that this form and the modification are shown for purposes of illustration and that the invention may be further modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a compressor, in combination, a casing containing intermeshing rotors oi the helical lobe and groove type, an intake port at one end of said casing, a discharge port at the opposite end of said casing, an auxiliary discharge port between the ends of said casing, valve means actuated by fluid supplied under pressure for closing said auxiliary discharge port, passage means ior conducting fluid to said valve means, means for supplying fluid under pressure to said passage means, a vent line connecting said passage means freely to exhaust, and valve means responsive to compressor intake pressure for closing said vent line.

2. In an air compresso in combination, 9. casing containing intermeshing rotors of the helical lobe and groove type, an intake port at one end of said casing, a discharge port at the opposite end of said casing, an auxiliary discharge port between the ends of said casing, valve means actuated by fluid supplied under pressure for closing said auxiliary discharge port, passage means for conducting fluid to said valve means, means for supplying fluid under pressure to said passage means, a vent line connecting said passage means freely to exhaust, and valve means responsive to compressor intake pressure and operative at a predetermined sub-atmospheric pressure for closing said vent line.

3. In combination, an air compressor of the intermeshing helical rotor type including a casing and inter-meshing rotors, intake means, and a discharge opening into communication with which the pockets formed by the coaction of the rotors come at the end of a predetermined range of compression, said casing having another discharge opening which the pockets formed by the coaction of the rotors reach before they attain to the first mentioned discharge opening, a valve for closing said second discharge opening, a conduit for conducting liquid to the valve, means 17 for supplying liquid under pressure to the conduit, a single vent line connecting the conduit freely to exhaust, and a vent line-control valve responsive to compressor intake pressure and operative at a predetermined sub-atmospheric pressure for closing said vent line.

4. In combination, a compressor of the intermeshing helical rotor type including a casing and intermeshing rotors, intake means, and a discharge opening into communication with which the pockets formed by the coaction oi the rotors come at the end of a predetermined range 01' compression, said casing having another discharge opening which the pockets formed by the coaction of the rotors reach before they attain to the first mentioned discharge opening, a valve for closing said second discharge opening, and hydraulically operated, valve-controlled means operated by liquid supplied thereto for actuating said opening-closing valve to closed position and a valve for venting liquid from said last mentioned means, said vent valve normally open, but closed when intake pressure falls below a. predetermined value.

WIN WITHER PAGET.

18 nnramzncss cr'ran' The following references are of record in the file of this patent:

5 UNITED STATES PATENTS Number Name Date 397,337 Buliard Feb. 5, 1889 1,111,498 Rotter Sept. 22, 1914 1,177,898 Rimmer Apr. 4, 1916 1,669,050 Grant May 8, 1928 1,686,505 Stastny Oct. 2, 1928 2,044,867 Woodard June 23, 1936 2,111,568 Lysholm et a] Mar. 22, 1938 2,174,522 Lysholm Oct. 3, 1939 15 2,217,364 Halford et a1. Oct. 8, 1940 2,301,251 Woods et al Jan. 5, 1943 2,316,416 Gregg Apr. 13, 1943 2,358,815 Lysholm Sept. 26, 1944 20 FOREIGN PATENTS Number Country Date 384,355 Great Britain Dec. 8, 1932 

